feat(macros): auto-generate get_info and default router (#785)

* feat(macros): auto-generate get_info and default router

* docs: simplify examples and docs with new defaults

* feat(macros): add tool_router(server_handler) to elide separate #[tool_handler] impl

* docs: add Tools section to README and simplify calculator examples with server_handler

examples/transport/src/tcp.rs

@@ -13,7 +13,7 @@ async fn server() -> anyhow::Result<()> {
     let tcp_listener = tokio::net::TcpListener::bind("127.0.0.1:8001").await?;
     while let Ok((stream, _)) = tcp_listener.accept().await {
         tokio::spawn(async move {
-            let server = serve_server(Calculator::new(), stream).await?;
+            let server = serve_server(Calculator, stream).await?;
             server.waiting().await?;
             anyhow::Ok(())
         });